This application claims priority to prior application JP 2002-322982, the disclosure of which is incorporated herein by reference.
The present invention relates to a housing having an electromagnetic wave shielding function and a waterproof function.
A measure to counter electromagnetic waves is required for communications devices or electronic devices and, particularly when disposed outdoors, a waterproof measure is also required for them. Accordingly, housings for those devices are expected to have an electromagnetic wave shielding function and a waterproof function.
The housing of this type is disclosed in, for example, JP-A-2001-160697, and comprises a box having an opening on one side thereof, and a cover closing the opening. The box is made of magnetic metal and has an edge portion defining the opening. The cover is made of magnetic metal and has a groove confronting the edge portion of the box
For sealing between the box and the cover, a gasket is placed in a groove formed on the edge portion of the box. The gasket has a structure wherein conductive electromagnetic wave shielding rubber is disposed on the surface of highly elastic rubber excellent in restoration against compression.
After placing the gasket in the groove on the edge portion of the box, an electronic circuit component is received in the box. Then, the cover is put on the box, and the box and the cover are fixed together by fixing means whit pressing the cover against the gasket. As a result, electromagnetic wave shielding and waterproofness are ensured between the box and the cover.
However, inasmuch as the foregoing housing is configured such that the cover is pressed against the separately formed gasket received in the groove on the edge portion of the box, gaps are liable to occur between the box and the cover. Specifically, since the electromagnetic wave shielding rubber forming the surface of the gasket is relatively poor in restoration against compression, a contact between the cover and the gasket tends to be a line contact, and besides, dispersion of components constituting the housing, which is caused upon manufacturing them, can not be absorbed, and therefore, possibility is high that the foregoing gaps are generated. When the gaps are generated, there arise problems of invasion of electromagnetic waves into the housing, leakage of electromagnetic waves to the exterior of the housing, and invasion of water into the housing. Accordingly, sufficient electromagnetic wave shielding and waterproof functions can not be achieved.
It is therefore an object of the present invention to provide a housing that has sufficient electromagnetic wave shielding and waterproof functions even if there is dispersion in material or processing accuracy.
Other objects of the present invention will become dear as the description proceeds.
According to an aspect of the present invention, there is provided a housing comprising a first housing component made of magnetic metal and having a first surface, a second housing component made of magnetic metal and having a second surface confronting the first surface, the second housing component being cooperated with the first housing component to define a space, and a sealing structure providing an electromagnetic wave shielding function and a waterproof function between the first and second housing components. The sealing structure comprises a groove portion formed on the first surface and extending around the space, a first seal member formed by being directly applied into the groove portion, the first seal member having relatively low hardness to be compressible, a second seal member formed by being applied onto the first seal member, the second seal member having relatively high hardness, flexibility, and conductivity, and a pressing portion formed on the second surface to correspond to the groove portion, the pressing portion pressingly deform the second seal member so as to be brought into surface contact with the second seal member.